There are many applications for subterranean structures such as trenches. Many manufacturing facilities use water throughout the plant for a variety of functions and thus require drainage systems to collect, remove and/or recycle the water. For outdoor applications, many industrial and commercial sites require drainage trenches and catch basins in order to direct rainwater to underground storm sewers and prevent flooding.
Trenches for such purposes are generally formed by pouring a moldable trench forming composition such as concrete around a form that has been placed in a ditch dug in the ground. The concrete is poured around the form and allowed to set. After the concrete has set, the form is removed so that the trench may be readied for use.
The most common form assembly used in the creation of a trench includes wood sheeting or planks and a supporting frame/strut structure that are secured within the ditch. The concrete is then poured between the ground wall and the sheeting/planks. The sheeting/planks and surrounding ground support the concrete while it sets to form the trench. The sheeting/planks and supporting frame are broken down and removed from the trench following the setting of the concrete. Since the sheeting/planks for this application are not prepared with great attention to surface character, it is likely that the wood texture and thus the trench surface is relatively rough and grainy, reducing the flow efficiency of the completed trench.
It can be appreciated that in circumstances where a long trench is required, a great deal of sheeting or many planks need to be secured together end to end in order to construct the form for the trench. Labor costs to complete the form are often excessive. This is particularly true since intricate rib work is often required to support the sheeting/planks in position against the relatively high pressures exerted by the heavy concrete. Additionally, there is often a precise pitch that is required from one end of the trench to the opposite end to provide proper drainage. The skill and care that is required in cutting and constructing the wood sheeting/planks to produce a form of desired shape and needed pitch significantly increases the labor time required and thus the overall construction cost for the trench.
Further, a grate is often supported over the trench by means of a pair of spaced frames that are set in the concrete. Unless these frames are maintained in proper alignment in a common plane during the pouring and setting of the concrete, the grate held in the frames will be unstable and prone to rocking when weight from, for example, a vehicle is applied. This condition may lead directly to damage to the grate and/or the frames and possibly even the surrounding concrete. In extreme cases, the grate may even become dislodged from the frames leaving the top of the trench open. Possible serious injury may result from such a safety hazard. Accordingly, it should be appreciated that extreme care must be exercised when constructing the form and positioning the frames relative to the form. The time necessary to exercise this care also adds significantly to the labor costs. In addition, a great deal of time is required to dismantle and remove the form following the setting of the concrete.
In some situations, precast trenches are used to avoid some of these difficulties. In general these assemblies are preformed metal assemblies that are placed in a ditch and are intended to permanently remain after concrete is poured around it for stabilization and support. However, such precast assemblies are expensive, especially in situations where the application requires unique customization.
A need is thus identified for an easier and quicker method of forming trenches, particularly, for industrial and commercial applications. The present invention is designed to fulfill these needs. The present trench forming assembly is inexpensive to fabricate and use and substantially reduces the time required to complete the trench for operative use. The invention is very versatile, adapted to be customized and adjusted to meet on-site specifications. The use of the invention provides a completed trench that efficiently blends into the operative environment.